private void checkExpression(@NotNull PsiExpression expression) {
   if (expression.getParent() instanceof PsiParenthesizedExpression) {
     return;
   }
   final PsiType expressionType = expression.getType();
   if (expressionType == null
       || expressionType.equals(PsiType.VOID)
       || !TypeConversionUtil.isPrimitiveAndNotNull(expressionType)) {
     return;
   }
   final PsiPrimitiveType primitiveType = (PsiPrimitiveType) expressionType;
   final PsiClassType boxedType = primitiveType.getBoxedType(expression);
   if (boxedType == null) {
     return;
   }
   final PsiType expectedType = ExpectedTypeUtils.findExpectedType(expression, false);
   if (expectedType == null || ClassUtils.isPrimitive(expectedType)) {
     return;
   }
   if (!expectedType.isAssignableFrom(boxedType)) {
     // JLS 5.2 Assignment Conversion
     // check if a narrowing primitive conversion is applicable
     if (!(expectedType instanceof PsiClassType) || !PsiUtil.isConstantExpression(expression)) {
       return;
     }
     final PsiClassType classType = (PsiClassType) expectedType;
     final String className = classType.getCanonicalText();
     if (!convertableBoxedClassNames.contains(className)) {
       return;
     }
     if (!PsiType.BYTE.equals(expressionType)
         && !PsiType.CHAR.equals(expressionType)
         && !PsiType.SHORT.equals(expressionType)
         && !PsiType.INT.equals(expressionType)) {
       return;
     }
   }
   if (ignoreAddedToCollection && isAddedToCollection(expression)) {
     return;
   }
   registerError(expression);
 }
 private boolean isAddedToCollection(PsiExpression expression) {
   final PsiElement parent = expression.getParent();
   if (!(parent instanceof PsiExpressionList)) {
     return false;
   }
   final PsiExpressionList expressionList = (PsiExpressionList) parent;
   final PsiElement grandParent = expressionList.getParent();
   if (!(grandParent instanceof PsiMethodCallExpression)) {
     return false;
   }
   final PsiMethodCallExpression methodCallExpression = (PsiMethodCallExpression) grandParent;
   final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
   @NonNls final String methodName = methodExpression.getReferenceName();
   if (!"put".equals(methodName) && !"set".equals(methodName) && !"add".equals(methodName)) {
     return false;
   }
   final PsiExpression qualifier = methodExpression.getQualifierExpression();
   return TypeUtils.expressionHasTypeOrSubtype(
           qualifier, CommonClassNames.JAVA_UTIL_COLLECTION, CommonClassNames.JAVA_UTIL_MAP)
       != null;
 }